新药研发费用及周期的持续增长，已不能满足现有疾病治疗所需，开发现有药物的新用途成为药物研发的一种重要策略。Tyrphostin AG490是一种对JAK/STAT信号通路有抑制作用的抗肿瘤化合物，前期结果表明，其对丙型肝炎病毒复制所必需RNA聚合酶NS5B的活性有明显的抑制作用，暗示其作为一种抗病毒化合物的潜力，但具体的抑制机理并不清楚。本项目拟结合氨基酸定点突变和NS5B活性检测模型，在体外研究tyrphostin AG490与NS5B的相互作用位点。同时结合实验室已有的HCV复制子体内活性分析检测体系，探索tyrphostin AG490通过NS5B蛋白作用于NF-κB信号通路的分子机理，主要包括NF-κB信号通路蛋白的变化及其介导的下游相关基因表达是否受tyrphostin AG490所影响。本项目对已有抗肿瘤化合物的新应用及新作用机制进行研究，为同时治疗HCV和肝癌提供理论依据。

The current costly and time-consuming paradigm of drug discovery is ill-equipped to combat rapidly emerging diseases, such as drug-resistant bacteria and virus. One of the strategies is to identify new uses for existing drugs. Tyrphostin AG490 was mostly used as an antitumor compound though inhibiting JAK/STAT signaling pathway. In our previous study, tyrphostin AG490 had a significant effect on HCV NS5B polymerase activity. As a potential anti-HCV compound, the molecular mechanism of tyrphostin AG490 inhibiting NS5B polymerase remains to be elucidated. In this project, site directed mutagenesis will be performed to study binding site(s) of tyrphostin AG490 on NS5B polymerase using in vitro anti-NS5B polymerase activity model. Subsequently, in vivo mechanism of tyrphostin AG490 on NF-κB signaling pathway mediated by NS5B polymerase will be studied, including a number of proteins and genes that are part of NF-κB signaling pathway most likely to be affected by tyrphostin AG490. This project studies new aspects of anti-tumor compound tyrphostin AG490 which shows the possibility of developing compounds act as both anti-HCV and anti-tumor drugs.